Unnamed (southeast of Upper Copper Lake)

Occurrence, Inactive

Commodities and mineralogy

Main commodities Au; Mo
Other commodities Cu
Ore minerals chalcopyrite; molybdenite; pyrite

Geographic location

Quadrangle map, 1:250,000-scale IL
Quadrangle map, 1:63,360-scale C-3
Latitude 59.5894
Longitude -154.0959
Nearby scientific data Find additional scientific data near this location
Location and accuracy This occurrence is at an elevation of about 1,000 feet on the north slope of the divide between Upper Copper Lake and Boot Lake. It is about in the center of the S1/2 NE1/4 sec. 7, T. 7 S., R. 28 W., Seward Meridian. The location is accurate within about 0.5 mile. The site is locality 13 of Detterman and Cobb (1972).

Geologic setting

Geologic description

This occurrence is near the contact between granitic plutons of Tertiary and Cretaceous or Tertiary age (Read, 1967; Detterman and Reed, 1980). It consists of pyritized, argillized, and sericitized(?) granitic intrusive rock in a 400-foot-long exposure along a fault-controlled, unnamed northerly-flowing stream. The granitic rocks are cut by a mafic dike. The altered rocks contain disseminated flakes of molybdenite. Copper and molybdenum occur in anomalous concentrations in stream-sediment samples collected below the occurrence (Reed,1967), suggesting that the occurrence also contains chalcopyrite. Reed's rock samples, however, did not detect the gold reported by Detterman and Cobb (1972). The fault that controls the exposure may be a splay of a shear zone extending northeastward through the Meadow Lake valley (Reed, 1967).
Geologic map unit (-154.098048804052, 59.5887289031636)
Mineral deposit model Porphyry Cu-Mo (Cox and Singer, 1986; model 21a).
Mineral deposit model number 21a
Age of mineralization Probably Tertiary.
Alteration of deposit Pyritization and argillic and sericitic(?) alteration.

Production and reserves

Workings or exploration Exploration consists of reconnaissance geologic mapping and rock and stream-sediment sampling. Reed's (1967) stream-sediment samples were anomalous for copper and molybdenum, but his rock samples did not detect the gold reported by Detterman and Cobb (1972).
Indication of production None